Bending fatigue life characterisation of direct metal laser sintering nickel alloy 718

Abstract

Bending fatigue behaviour of direct metal laser sintering (DMLS), Nickel (Ni) Alloy 718 has been assessed as preliminary qualification to additively manufacture advanced gas turbine engine components. Motivation for this work comes from the possibility of using DMLS to improve functionality of hot‐section components. By using DMLS, turbine blades and heat exchangers cooling passages can be enhanced, leading to improved engine performance. This study focuses on vibratory high cycle fatigue (HCF) assessment of DMLS Ni Alloy 718 from two suppliers. Specimens were fatigued via vibration‐based bending and compared with published rotating bending cold‐rolled Ni Alloy 718. Tensile analysis and microscopy were also conducted to understand fatigue and fracture trends. HCF, tensile properties and microscopy comparisons show that fatigue and strength of DMLS Ni may be sensitive to post‐fusion treatments. Nonetheless, fatigue performance of DMLS Ni compares well with rotating bending fatigue of cold‐rolled Ni.

Influence of the build orientation on the fatigue strength of EOS maraging steel produced by additive metal machine

“…Afterwards, the specimens underwent ageing treatment by heating in air up to 490 °C for 6 h, following the recommendations by the material powder manufacturer . As mentioned in the Introduction section, the ageing treatment is particularly effective at reducing the residual stresses, thus enhancing the fatigue response of the built parts . The aged samples were again treated by microshot‐peening to reduce the risk of opening up pores during the subsequent polishing.…”

“…24,25 As mentioned in the Introduction section, the ageing treatment is particularly effective at reducing the residual stresses, thus enhancing the fatigue response of the built parts. [11][12][13][14][15] The aged samples were again treated by microshot-peening to reduce the risk of opening up pores during the subsequent polishing. Shot-peening is also particularly effective at homogenizing and reducing the surface residual stress state that may be induced by the DMLS treatment.…”

“…Interesting points stand in the issue of a potentially good response to vibrations of the single‐component structure and in the no need for welded joints to connect blades. This ensures an easier manufacturing without residual stresses arising from the welding process . However, the same reference points out that the AM process itself is likely to induce residual stresses and porosities that may trigger crack nucleation.…”

“…This ensures an easier manufacturing without residual stresses arising from the welding process. 11 However, the same reference points out that the AM process itself is likely to induce residual stresses and porosities that may trigger crack nucleation.…”

Effects of build orientation and thickness of allowance on the fatigue behaviour of 15–5 PH stainless steel manufactured by DMLS

“…Nowadays, there is an increasing interest towards Additive Manufacturing ( AM ) techniques, as this technological process is potentially capable of producing even complexly shaped parts in a relatively short time . In addition, the parts can be easily built, with a high level of flexibility, starting from a CAD model .…”